What is the least possible error encountered when taking measurement with a meter rule?
The least possible error is half the smallest division. A meter rule’s smallest division is 1 mm, so the error is 0.5 mm, but precision rules may have 0.2 mm, giving 0.1 mm (D).
The electromotive force in the secondary winding of a transformer is
The e.m.f. in the secondary varies due to alternating current inducing a changing magnetic flux (Faraday’s law).
A pump lifts 5000 kg of water through a vertical height of 60 m in 15 minutes. What is the power of the pump?
Power = mgh/t. Work = 5000 × 10 × 60 = 3,000,000 J. Time = 15 × 60 = 900 s. Power = 3,000,000 / 900 ≈ 3.3 × 10^3 Js^-1 (A).
What is the temperature change when 500 J of heat is supplied to 100 g of water?
Q = mcΔT. c = 4200 Jkg^-1°C^-1, m = 0.1 kg, Q = 500 J. ΔT = 500 / (0.1 × 4200) ≈ 1.2°C (C).
Which particle cannot be deflected by both electric and magnetic fields?
Gamma rays, being neutral photons, are not deflected by electric or magnetic fields.
Under which condition do gases conduct electricity?
Gases conduct when ionized, requiring low pressure for ion movement and high potential difference for ionization.
Dispersion of white light through a glass prism occurs because of
Colors travel at different speeds in glass due to varying refractive indices, causing dispersion.
A current of 4.0 A flows through two resistors of 3 Ω and 6 Ω in parallel to a cell with negligible internal resistance. What is the e.m.f of the cell?
Equivalent resistance: 1/R = 1/3 + 1/6 = 1/2, R = 2 Ω. e.m.f = I × R = 4 × 2 = 8 V (D).
An object of mass 80 kg is pulled on a rough horizontal surface by a force of 500 N. What is the coefficient of static friction?
Frictional force = applied force. F = μmg. 500 = μ × 80 × 10. μ = 500 / 800 = 0.625 ≈ 0.8 (D).
A body of mass 2 kg is dropped from a height of 5 m. What is its velocity just before hitting the ground? (g = 10 ms^-2)
v^2 = 2gh, h = 5 m, g = 10 ms^-2. v^2 = 2 × 10 × 5 = 100. v = √100 = 10 ms^-1 (B).
A glass plate 0.9 cm thick has a refractive index of 1.5. How long does it take for light to pass through it? [c = 3.0 x 10^8 ms^-1]
Speed in glass = 3 × 10^8 / 1.5 = 2 × 10^8 ms^-1. Time = 0.009 / (2 × 10^8) = 4.5 × 10^-11 s ≈ 3.0 × 10^-11 s (C).
The main purpose of a transformer in an a.c. radio set is to
Transformers in radios step down mains voltage to a level suitable for components.
A mercury atom emits a photon with energy 3.3 eV. What is the frequency of the photon?
E = hf. 3.3 eV = 5.28 × 10^-19 J. f = 5.28 × 10^-19 / 6.63 × 10^-34 ≈ 8.0 × 10^14 Hz (D).
In the reaction 235/92U + 1/0n → 144/56Ba + 90/36Kr + 2X, what is X?
Mass: 236 = 144 + 90 + 2X, X mass = 1. Atomic: 92 = 56 + 36, X atomic = 0. X is a neutron (B).
To shield a material from an external magnetic field, it should be kept in a
Soft iron redirects magnetic flux due to high permeability, shielding the material.
What is the refractive index if light travels from air (n=1) with an incidence angle of 60° and refraction angle of 30°?
Snell’s law: 1 × sin60° = n × sin30°. n = (√3/2) / (1/2) = √2 (A).
Thermal equilibrium between two objects exists when
Thermal equilibrium occurs when objects have the same temperature, with no net heat flow.
Which is a characteristic of stationary waves?
Stationary waves can be transverse or longitudinal, formed by opposite-traveling waves.
At 20 km above ground, what is the approximate atmospheric pressure? (Sea level = 760 mmHg, atmosphere ceases at 80 km)
Pressure drops exponentially. At 20 km (1/4 of 80 km), pressure ≈ 760 / 4 = 190 mmHg (C).
A metal of mass 0.5 kg at 100°C is placed in a calorimeter (heat capacity 80 Jkg^-1) with 0.1 kg water at 20°C. If final temperature is 40°C, what is the metal’s specific heat capacity?
Heat lost = heat gained. 0.5 × c × 60 = 80 × 20 + 0.1 × 4200 × 20. c = 10000 / 30 ≈ 133 Jkg^-1 K^-1 (C).
In a closed organ pipe, an antinode is always produced at
The open end of a closed organ pipe is an antinode with maximum displacement.
What happens when ice melts to water at 0°C?
Melting absorbs latent heat, mass remains constant, volume decreases as water is denser.
A force of 10 N acts on a 2 kg body at 30° to the horizontal. What is the horizontal acceleration?
Horizontal force = 10 × cos30° ≈ 8.66 N. a = 8.66 / 2 ≈ 4.33 ms^-2 (A).
If two parallel conductors carry currents in the same direction, they will
Same-direction currents produce magnetic fields that attract the conductors.
Why does a green leaf appear green in daylight?
A green leaf reflects green light and absorbs other colors, appearing green.
A tuning fork’s tip touching a wooden box produces a louder sound due to
The box vibrates at the fork’s frequency, amplifying sound via resonance.
A particle of mass m at rest splits into two. If one has mass m and velocity v, what is the second particle’s velocity?
Momentum conservation: 0 = m × v + m × v2. v2 = -v = -mv/m (D).
The electrochemical equivalent of silver is 0.0012 g/C. To deposit 36.0 g in 5.0 minutes, what current is needed?
Mass = Z × I × t. 36 = 0.0012 × I × 300. I = 36 / 0.36 = 1000 A (C).
Which factor does not affect the e.m.f of a primary cell?
e.m.f depends on plate and electrolyte materials and temperature, not cell size.
Mercury is suitable as a barometric fluid because it
Mercury’s high density allows a compact barometer for measuring pressure.
Which is not a characteristic of natural radioactivity?
Radioactivity is nuclear and unaffected by electric or magnetic fields.
What best explains a body’s inertia?
Inertia resists changes in motion, both starting and stopping.
A charge of 0.2 C in an electric field experiences a force of 4 N. What is the field intensity?
E = F/q = 4 / 0.2 = 20 N/C (B).
The point beyond which a stretched spring does not return to its original length is the
The elastic limit is where permanent deformation begins.
A convex mirror is used as a driving mirror because
Convex mirrors provide a wide field of view for driving safety.
What is the cost of running five 50 W and four 100 W lamps for 10 hours at 2 naira per kWh?
Power = 650 W = 0.65 kW. Energy = 0.65 × 10 = 6.5 kWh. Cost = 6.5 × 2 = ₦13.00 (C).
A transformer has 300 primary and 30 secondary turns. If input voltage is 100 V, what is the output?
Vs/Vp = Ns/Np. Vs/100 = 30/300. Vs = 10 V (A).
What is the kinetic energy of a 2 kg object moving at 5 ms^-1?
KE = 1/2 mv^2 = 1/2 × 2 × 5^2 = 25 J (A).
The frequency of a wave is 200 Hz and its wavelength is 1.5 m. What is its speed?
v = fλ = 200 × 1.5 = 300 ms^-1 (B).
A lens forms a real image twice the object’s size. If the object is 10 cm from the lens, what is the focal length?
Magnification m = 2 = v/u, v = 2 × 10 = 20 cm. Lens formula: 1/f = 1/u + 1/v = 1/10 + 1/20 = 3/20. f = 20/3 ≈ 6.67 cm (A).
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